A researcher stumbles upon a group of young children, who can communicate without being connected, but he’s shocked to discover that the children wish to eradicate their elders–and particularly the researcher.

I agree with Odie, if you can say something with one or two words don't use more,

A group of kids who can 'communicate telepathically'... gets rid of extra words.

The logline should not be about the lead being shocked, it should be about what he does about the situation.

Consider the following:
1. What is your protag’s field of research?
2. “communicate without being connected” – telepathic?
3. What is an elder - their parents?
4. Why do these children want to snuff him out? To keep their secret of world domination - what is their goal?

Keep going!

BTW: Checkout 1995’s “Village of the Dammed” and the 81 classic “Scanners” for some fun research.